Semi-plug piston-valve and piston.



J. T. WILSON SEMI-PLUG PISTON VALVE AND PISTON.

APPLIUATIUN FILED MAB. 9, 1907.

Patented Nov. 17,1908.

3mm ufon JOHN THOMAS WILSON, OF JERSEY SHORE, PENNSYLVANIA.

SEMI-PLUG PISTON-VALVE AND PISTON.

Specification of Letters Patent.

latented Nov. 17, 1908.

Application filed Marcus, 1007. Serial No. 361,453.

'Sh all whom it may concern:

Be it known that I, JOHN THOMAS WIL- son, a citizen of the United States, residing at Jersey Shore, in the county of Lycoming and State of Pennsylvania, have invented new and useful Im )rovements in Semi-Plug Piston-Valves and istons, of which the following is a specification.

The invention relates to piston valves and pistons, and especially to the packing for semi-plug valves, the object being the provision 0. a packing, first, having snap or hearing rin s which shall retain their normal paralle positions when in service and not move laterally or tip sidewisc and occupy positions where the edges of the rings would be liable to engage or catch into the metallic edges of the cage or lining which bound the ports; second, which may collapse when the steam is shut off and the locomotive drifting so the air compressed by the piston of the engine may was-s between the cage and the packing; and, third, which shall admit of the snap rings thereof being quickly expanded under steam pressure prior tothe expansion of the wedge ring of the packing.

. With these main ends in view my inven tion consists in certain novelties of construction and combinations of parts as hereinafter application of the principle and to attain the desired results.

Figure 1 shows a piston valve, )art thereof being in section. Fig. 2 is an enlarged view through the packing. Fig. 3 shows the wedge ring joint. Figs. 4, 5, and'fi are opposite side and top' plan views of a snap ring joint. Fig. 7 is a cross section of Fi 6 between the free ends of the ring and t rough the bottom and side joint plates.

Referring to the several views, the numeral 1 designates the s 001 of the valve; 2, the flange of the spec 3, the follower; 4, the flange of the follower; 5, the rim of the follower Hi, the joint between the rim of the follower and the end of the spool; 7, the perforated hub of the follower; 8, the valve stem of any approved construction; 9, a retaining bolt threaded at the end not shown and engaging a threaded hole in the follower at the opposlteend of the s 001 body; 10, the

- Snap rings; 11. the vertica plane side of a as the pressure becomes equalized.

sna ring; 1:2, the opposite beveled side or suri aee; 13, a circular roovc near the outer edge of the beveled sur are; 14, the free ends of the snap ring; 15, the bottom joint plate; 16, machine screws which secure one end of the joint plate to one end of the snap ring; 17, a side joint plate, 18, machine screws which secure one end of the side joint plate to the free end of t'hesna p ring opposite to the end of the snap ring to which the bottom joint plate is seem-ed; 19, the integral wall rings; 20, the outer beveled surface in con tact with the beveled surface of a snap ring; 21. the inner beveled surface in contact with a beveled surface of a wedge ring; 22, the wedge ring; 23, the joint plate; 24 a spring plate; 25, machine screws passed through the ends of the wed e rin joint. plate, and spring plate; 26, t e wic e ring; 27, the free ends of the wide ring; 28, holes through the wide ring; 29, tongues at opposite edges of the wide ring whichfit within the grooves 13 in the snap rings; 30, circular parallel threads about 1/32 wide at their outer surfaces in connection with the wide ring; 31. a series of small passages made in the end of the spool and follower and extended under the packing; 32, an open space beneath the packyng; 33, are a. series of ports from the passages 31 and located directly beneath the snap ringsumd 34 is a part of the cage.

The relative locations of the several parts and elements are clearly shown by the sev eral figures.

The mode of operation is as follows: As suming the piston valve to be in operative position within a cylinder or cage with suitable openings or ports leadin to the main piston cylinder, and steam a mitted to the space between the ends of the spool, the" steam will enter the small passages 31 and be delivered under great velocity through the ports 33 and in jets which will strike the under surfaces of the snap rings and ex pand them against the surface of the ea c. The wedge ring will then be fully expant ed Since the :wall rings are integral and cannot expend they are forced sidewise under the pressure of the expanding wedge ring and press and hold the snap rings in their previously expanded positions against the flanges of the spool and follower and with their outer surfaces against the cage. \Vhen' the piston moves, for example, towards the.

right and passes over a port, the wide ring holds the snap rings parallel so they cannot tip sidewise and their ed es catch the edges 0 the metal bounding t e-port. Nor can the snap rin 5 ex and into the port or 0 ening, inasmuc i as both sna rings are hel by the beveled surfuc'esof tie wall rings As the wide ring is provided with holes 28 steam enters beneath the rim when the same is in line with the port. go secure an approximately equal pressure upon the to an bottom surfaces of this wide ring at a 1 positions of its travel the threads 30 are provided uporrthe outer surface of the ring, the spaces between said threads containing steam even when the edge or entire area of the ring has moved to one side of the port. In other words the wide ring is practically balanced at all positions ofrits travel. Moreover, it is obvious that the snap rings will at all times be held against the surface of the cylinder or cage, as the area of the packing exposed to pressure from the port is always less than the area of the under surface of the packing adjacent the rim of the follower to which steam is admitted by we of the passages 31 in 'the spool body. he outersurfaces of the threads upon the wide ring touch the inner surfaces of the cage and assist in preventing the sna rings from expanding into the port, an also prevent an excessive expansion and friction of the wide ring itself when at one side of a port should thc'tongue of the ring loosely tit the groove in the side of the snap ring. When steam is cut off and the locomotive is in motion the wedge rin contracts and this allows the snap rings also to contract so-that air under compression from the port may pass between the packing and the ca e. The snap rings are o course-made smaller than the internal circumference of the cage and are loose in the cage when the piston valve is placed in working position within the cage so the said rings are not under tension whe the engine is drifting.

From the fomgoingdescription taken in connection with the drawing it is clear that I have produced a wide ring which holds theisnap rings from tipping sidewise and 'is subject to about equalpressure upon both outer and inner surfaces and hence is practically balanced, and cannot press excessively against the surface of the cage; secondlyi that is collapsible so it will move freely w iin' the cage when the locomotive i s drifting; and, thirdly, that will allow of the expansion of the sna rings, or allow' the snap rings to take the ead in expanding, before thewedge ring expands wedge rm";

packing, firstly, having a sufficiently to lock the snap rin I have thus produced a semi-plug va ve having greater advanta es than both the common plug valve and t e snap ring valve and without the disadvantages of either. i

It is to be, understood that the principle may be embodied in connection with a. sm-

gle snap ring, a wall ring, and a wed e ring, when said rings are arranged so 1; e snap ring takes the lead of the wedge ring in the snap IlIlgS in ets.

The combination with a piston valve having a packing comprising an ex ansible wide ring, two non-e'xpansible wal rin s; two expansible snap rings, and an expansible means being provided for introducing ive steam to the under surfaces of the snap rin s and subsequently to the under surface of the wedge ring.

4. The com'blnation with a piston valve, of a packing comprising a wide ring, two

snap rings, two wall rings, and a wedge ring; the said valve being provided with a series of passages with ports which arts are adapted tovdischarge steam direct y to the under surfaces of the snap rings.

Apacking for pistons having a snap ring, a wall ring, ttlltltlll expansible wedge rhig, in combination with a seat in the piston; and means for introducing steam beneath the rings and expanding the snap ring in advance of the complete expansion of the wedge ring. r 6. The combination with a piston, of a packing comprising'ga lurality of expansible rlngiwr non-expansib e ring, and means for causingone of said ex ansible rings to exs pand in advance oftie expansion of the other. In testimony whereof utlix my signature in presence of two witnesses;

JQIIN THOMAS \VILSON. \Vit nesscs:

JOHN T. llrxr'r, L. M. Borne. 

